One-Pot Synthesis of Indoles by a Sequential Ugi-3CR/Wittig Reaction Starting from Odorless Isocyanide-Substituted Phosphonium Salts

Novel Metal-Free Synthesis of 3-Substituted Isocoumarins and Evaluation of Their Fluorescence Properties for Potential Applications

A novel metal-free synthesis of 3-substituted isocoumarins through a sequential O-acylation/Wittig reaction has been established. The readily accessible (2-carboxybenzyl)-triphenylphosphonium bromide and diverse chlorides produced various 1H-isochromen-1-one in the presence of triethylamine, employing sequential O-acylation and an intramolecular Wittig reaction of acid anhydride. Reactions using these facile conditions have exhibited high functional group tolerance and excellent yields (up to 90%). Moreover, the fluorescence properties of isocoumarin derivatives were evaluated at the theoretical and experimental levels to determine their potential application in fluorescent materials. These derivatives have good photoluminescence in THF with a large Stokes shift and an absolute fluorescence quantum yield of up to 14%.

Synthesis of Luminescent Indolo[2,1-b]quinazolin-6(12H)-ones via a Sequential Ugi/Iodine-Promoted Cyclization/Staudinger/Aza-Wittig Reaction

A new efficient synthesis of indolo[2,1-b]quinazolin-6(12H)-ones via a sequential Ugi/iodine-promoted cyclization/Staudinger/aza-Wittig reaction was developed. The acid catalyzed three-component reactions of 2-azidobenzaldehydes, 2-[2-(trimethylsilyl)ethynyl]benzenamines (or o-aminoacetophenones), and isocyanides gave Ugi-3CR intermediates, which reacted subsequently with I2/DMSO and triphenylphosphine to produce indolo[2,1-b]quinazolin-6(12H)-ones in good overall yields. The obtained indolo[2,1-b]quinazolin-6(12H)-ones were all colored in bright red or orange. Their luminescent property was studied preliminarily and some of them showed high molar absorption coefficients, strong fluorescence emission intensity, and good absolute light quantum yields.

Camphorsulfonic Acid-Mediated One-Pot Tandem Consecutive via the Ugi Four-Component Reaction for the Synthesis of Functionalized Indole and 2-Quinolone Derivatives by Switching Solvents

A camphorsulfonic acid-mediated one-pot tandem consecutive approach was developed to synthesize functionalized indole and 2-quinolone derivatives from the Ugi four-component reaction by switching solvents. A reaction of the Ugi adduct in an aprotic solvent undergoes 5-exo-trig cyclization to form an indole ring. In a protic solvent, however, the Ugi adduct undergoes an alkyne-carbonyl metathesis reaction to form a 2-quinolone ring.

The Ugi three-component reaction and its variants

A broad variety of α-aminoamide-based compounds have been synthesized via the three-component version of the Ugi reaction (U-3CR) or by any of its variants (Ugi-Zhu-3CR, Orru-3CR, Ugi-4C-3CR, Ugi-Joullié-3CR, GBB-3CR, Ugi-Reissert-3CR, and so on).

Synthesis of iminoisoindolinones via a cascade of the three-component Ugi reaction, palladium catalyzed isocyanide insertion, hydroxylation and an unexpected rearrangement reaction

A robust ligand-free palladium-catalyzed cascade reaction for the synthesis of diversely substituted iminoisoindolinones has been developed. The cascade reaction involves isocyanide insertion into Ugi-3CR adducts, accompanied by unexpected hydroxylation and rearrangement.

Atom-economical, room-temperature, and high-efficiency synthesis of polyamides via a three-component polymerization involving benzoxazines, odorless isocyanides, and water

High-efficiency three-component polymerization involving benzoxazines, odorless isocyanides, and water to synthesize polyamide derivatives at room temperature was reported here.

Multifunctional odorless isocyano(triphenylphosphoranylidene)-acetates: synthesis and direct one-pot four-component Ugi/Wittig cyclization to multisubstituted oxazoles

A new one-step four-component synthesis of multisubstituted oxazoles has been developed.